Electrohydraulic operator



' Mgrcb'sl; 1942.l

E. E. ARNOLD ELECTRO-HYDRAULIC OPERATOR Filed Feb. 23, 1939 INVENTOR y fdl/wn fffgrn'o/a( ATTORNEY WITNESSES:

Patented Mar. 31,1942

UNITED STATES BATENT OFFICE 2,277,836 ELECTROHYDRAULIC OPERATOR Edwin E.

Arnold, rittsburgii, Pa., assigner to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa.,

i Pennsylvania l Y a corporation of Application February 23; 1939, serial No. 257,940 43 claims. (C1. eso-52) l My invention relates to an electro-hydraulic operating means and more specifically to one ,which converts rotation of a motor shaft into a linear movement of a push rod, thereby eecting a thrust or push whiclfiis useful, for example, in operating clutches, brakes, doors and numerous other apparatus.

One object oi my invention is to provide an I electro-hydraulic operator or Push lMotor which is simple and rugged in construction and which is of relatively small size, but the output ratingA of which is relatively high. l

Another object of my invention is to provide an electrofhyclraulic operator which.. employsia propeller-type pumpl instead of a centrifugal pump, for instance, thereby obtaining a higher power output for a given size of electro-hydraulic operator, and which develops a greater thrust in a shorter time interval and which may be reversed to speed up return motion as comparedy number of propeller pump unitsbeing variable,

hence providing a propeller pump whose output is nominated merely by addition or subtraction of one or more propeller pump units,

Other objects and advantages will become more apparent from a study of the following specification when considered in conjunction with the accompanying drawing, in which:

Figure l is a sectional view of an electrohydraulic operator employing certain features of my invention; and

Fig. 2 is a perspectiverexploded view of one of the propeller pump units which formspart of the multiple stage propeller pump.

Referring to Figure l, numeral I indicates a `casing or container which is partially lled with fluid, such as oil or the like. Mounted on the top of the casing is an electric motor 2. The electric motor 2 drives a propeller shaft 3 which extends into the pump chamber and which is held in position at its upper end` by bearing and journaled at the bottom thereof by a bearing Rigidly secured tothe drive shaft 3 by means ci is driven as one with the shaft a nut 5. are a number of propeller units 6,-each comprising a plurality of substantially radially extending propeller type blades as shown more 2. Thus the group of propellers 3. Each propeller unit includes a complementary stationary guide vane assembly 1 which comprises a ring-shaped element having a plurality of substantially radially inwardly extending guide vanes as shown more clearly in Fig. 2. A follow-up nut assembly 8, also having guide vanes to direct the flow clearly in Fig.

of fluid into the first stage propeller, rigidly clamps all of the stationary guide vanes in place, the lower guide vane assembly being seated on a shoulder 9 machined in the casing for that purpose. e

It will be noted that the follow-up nut assembly 8, together with its attached upstanding collar member 28, forms a stationary surface, hence the fluid 'adjacent thereto is not agitated so as to form a vortex or whirlpool aswould be the case if the propeller shaft were unshielded and were directly in contact with the fluid reservoir.

To further minimize the tendency for the fluid to become violently agitated or turbulent during operation of the pump, a curved shoulder 29 is provided internally the fluid in the path and direction as shown by the arrow (or in the opposite direction in the event of reversal of the motor).

By varying the number of propeller units, the output or'l the multiple stage propeller pump can be varied. A plurality of inlet ports IIJ are streamlined into the follow-up nut assembly to provide emcient flow into the first propeller. An

adjustable outlet valve II is provided which is situated immediately between the pump discharge and the pressure chamber I-2. There are two principal divisions within the casing I, both of which are preferably cylindrical, the one being the chamber in which the multiple propeller pump is located and the other being the piston or work chamber I3. A piston I4 is slidable within the piston chamber- I3. -A helical spring I5 surrounds the piston rod 20, and is guided at one end by bushing I6 and at the other end by collar I1. The spring I5 normally urgesthe piston I4 in a downward direction to aid in its return to normal position aftercompleting an upward movement. Spring I5 may be eliminated Jil the load is of such character as to afford return of the piston; for example, a spring-operated, motor-released brake, a heavy loadr lifted against gravity, etc.

The upstandingl projection I8 at the bottom of of the casing in order to guide agresse such as the threaded projection 2| to any suitable l0 means for connecting to a load resistance, such as a brake, door, etc. Any suitable linkages or power amplifying levers may, of course, be interposed between the piston rod andthe load resistance. An inlet plug 22 is provided for 15 filling the casing with fluid while an outlet plug 23 is provided for draining such fluid when desired.

The adjustable outlet valve II comprises a valve member 24 which is urged upwardly by a 20 light helical spring 25 so as to engage an adjustable screw or stop member 26 toregulate the back ow and hence the speed of return of the piston to its normal position.

The operation of the device is as follows: 25

When the electric motor 2 is energized and drives the drive shaft 3, it also drives all of the propeller units 6 forcing fluid downwardly in a direction which is Isubstantially parallel to the axis of the drive shaft, this direction of flow 30 being aided by the guiding effect of thev stationary guide vanes l. 'Ihe uid pressure developed meets little resistancein passing Valve member 24 downwardly, permitting free flow of fluid through the valve into the pressure or work- '35 ing chamber I 2, in which chamber sufficient pressure is developed to force piston I4 upwardly against the relatively light restraining action of spring I 5, at the same time pushing piston rod 20 upwardly, which, in turn, may operate any 40 suitable device such as a brake (not shown) or other load service. energized and the multiple stage propeller pump no longer functions, either the load, which has been raised, or the spring I5, or both will push piston I4, together with piston rod 20, downwardly finally seating the piston on member I8. In the course of such downward movement of the piston, the fluid in chamber I2 will flow back through the pump to the opposite side as will be obvious. The valve member 24 may be adjusted to cause a restriction to the backward flow of fluid upwardly through the propeller pump. The

amount of restriction ofthe valve I I is adjustable by adjusting the screw or stop member 26 and 55 the adjustment may be made to correspond to the desired return speed of the piston I4. The return stroke of piston I4 may also be speeded up by reenergizing the motor in reverse direc- ,tion to its normal operation.

Thus, in accordance with the above-described device, an electro-hydraulic operator is provided which employs a propeller-type pump. Such pump has many advantages over the centrifugaltype pump, as has been outlined in the objects of the invention. The advantages are: The provision of a higher maximum power out-put for a given size which therefore, requires less time for developing larger pressures; the provision of the ability to operate in reverse direction to speed up the return stroke; the provision of a multiple unit structure whose output may be changed by merely varying the number of propeller pump units; and the provision of a simple, rugged construction resultingin a smaller .but yet'v of a 75 A buffer washer4 I9 of re- 5 As soon as motor`2 is dehigher output rating than a correspondingly rated centrifugally operated pump.

I am, of course, aware that others, particularly after having had the benefit of the teachings of my invention, may devise other devices embodying my invention, and I, therefore, do not wish to be limited to the specic showings made in the drawing and the descriptive disclosure hereinbefore made, but wish to be limited only by the scope of the appended claims.

I claim as my invention:

l. A hydraulic operator including a fluid casing, 1a pair of substantially cylindrical chambers which are side by side with their axes in( `in a direction parallel to the axis of said drive shaft to create a differential in uid pressure on opposite sides of said piston thereby imparting motion thereto, a valve which is positioned between theoutlet of said pump and said piston for controlling the ow of fluid 'therebetween and springmeans which normally biases said valve in an almost closed or restricted position but which yieldsv and allows opening thereof in response to pressure developed by said pump, and means removed from said piston and immediately adjacent said valve and which extends through said casing immediately adjacent the outlet of said pump for adjusting the amount of normal restriction of said valve.

2. A hydraulic operator including a substantially cylindrical casing containing a fluid, a pair of substantially cylindrical chambers arranged side by side within said casing with their axes parallel to the axis of said casing and with their vadjacent ends in communication to allow flow of fluid therebetween, a motor mounted on the top of said casing and having a drive shaft extending into one of said cylindrical chambers, a

and an adjoining sleeve member which is rigidly secured to the wall of said one of the chambers and which has substantially radially inwardly extending guide vanes, said units being readily detachable and variable in number to change the capacity of the pump without affecting the casing structure, the plurality of propeller pump units comprising alternately arranged spider elements 0 and guide vanes thereby being arranged to force the fluid downwardly in the chamber parallel to the axis thereof, the second of said chambers containing a piston and spring means for 10rmally biasing said piston downwardly into cngagement with a lower wall portion of said cas- Aing and which is yieldably movable upwardly in response to pressure developed by said pump at the lowerend of said substantially cylindrical chambers, and an outlet port containing an adjustable valve for controlling the flow of fluid between the bottom surface of said piston and y said one of the chambers.

3. A hydraulic operator including a fluid casing, a pair of cylindrical chambers which are side by side with their axes in parallel relationship within said casing, the adjacent ends of said chambers being in communication to allow flowI of uid therebetween, one of said chambers containing a piston and the other of said chambers containing a pump including a drive shaft and a plurality of longitudinally disposed propeller pump units of the end discharge type, each p ropeller pump unit comprising anpropeller lblade unit rigidly secured to said drive shaft and adjacent guide vanes. which are secured to said chamber, extending radially inwardly thereof, thus combining to form a multiple pump comprising alternately disposed propeller blade units and guide vanes so yas to force the fluid in a direction parallel to the axis of said drive shaft, a

shoulder formed on the wall of said pump chamber for seating the lowermost. pump unit, said .pump chamber having athreade'd portion adjacentvthe uppermost pump unit, a follow-up nut unit in threaded relation therewith for clamp-k ing the respective pump units together therebymaking the pump units readily detachable and variable in number so as to vary the capacity of the pump without aiecting the vcasing structure, inlet ports contained within said follow-up nut unit, and an electric motor for driving said pump.

EDWIN E. ARNOLD. 

